The Institute of Medicine (April, 2013 meeting) identified elder abuse as an underappreciated public health problem. Possibly the greatest threat of elder abuse to residents in long-term care settings such as nursing homes that house large numbers of individuals with dementia, comes at the hands of other residents. Resident-to-resident elder mistreatment (R-REM) is a major problem that has received little attention. Growing clinical evidence suggests that R-REM is sufficiently widespread to be of concern, affecting negatively staff and residents' health and quality of life. Despite its frequent occurrence, R-REM is under-reported, in part due to the lack of efficient and effective institutional reporting mechanisms and/or guidelines. No evidence-based prevention interventions exist. In 2009 the applicant team, collaborating with geriatricians and gerontologists from major medical centers received funding from the National Institutes on Aging, Justice and the NY State Department-of-Health to conduct: the first in-depth study of R-REM in nursing homes, including qualitative in- depth case conferencing; and a longitudinal study of the effectiveness of a staff training program. The proposed project will use this unique, rich quantitative and qualitative dataset cross-sectionally and longitudinally to examine profiles of perpetrators and victims to inform future prevention interventions. Dissemination is planned at the state and national levels. The policy stakeholder, a member of a State regulatory agency will provide input such that future recommendations regarding R-REM profile-specific interventions are more likely to be adopted. This project has the potential to advance the science of identifying R-REM profiles, and will result in guidelines for developing future testable interventions to prevent R-REM with an overarching goal of enhanced quality of life for nursing home residents. The overall aim of the project is to perform exploratory hypothesis-generating secondary data analyses to address several research questions generated from the following specific aims: (1) describe typologies quantitatively (2) (2a) identify the longitudinal predictos of R-REM and R-REM subtypes (2b) examine the social determinants, and environmental contexts predictive of R-REM to inform intervention studies (2c) identify reported intervention strategies in terms of their relationship to repeat R-REM, and (3) examine longitudinally the contribution of resident characteristics, social determinants, environmental factors and R-REM typologies to adverse outcomes and quality-of-life. A major goal of this study is to provide the findings from which to design interventions to reduce the frequency of physical, verbal, sexual and psychological mistreatment experienced, and to thus enhance the quality of life of residents with high exposure, many of whom are unable to speak for themselves because of Alzheimer's disease. Advancing the state-of-science related to this little-studied phenomenon is an overarching goal.